Weekly Year 2: GIT Physiology Exam - May 15, 2026 (Section A

Question 1

Which of the following statements is FALSE regarding the gastrointestinal tract's regulation?

Accepted Answer

The submucosal plexus primarily controls motor functions of the GI tract. — The submucosal plexus (Meissner's plexus) primarily regulates glandular secretions and blood flow, while the myenteric plexus (Auerbach's plexus) is the primary controller of GI motility.

Question 2

Which tissue layer is primarily responsible for the propulsive and mixing movements of the gastrointestinal tract?

Accepted Answer

Muscularis externa — The muscularis externa, composed of inner circular and outer longitudinal smooth muscle layers, is responsible for the muscular contractions that drive peristalsis and segmentation, essential for digestion and motility.

Question 3

Which statement about bile is TRUE?

Accepted Answer

Bile salts are essential for the emulsification of fats. — Bile salts are amphipathic molecules that reduce the surface tension of large fat globules, breaking them down into smaller droplets (emulsification), thereby increasing the surface area for lipase action. Bile is produced by the liver and concentrated/stored in the gallbladder.

Question 4

Which statement regarding the swallowing reflex (deglutition) is FALSE?

Accepted Answer

The pharyngeal phase is voluntary. — The pharyngeal phase of swallowing is an involuntary, reflex action initiated by the presence of food in the pharynx. The voluntary phase is the oral phase.

Question 5

Which of the following statements concerning the intrinsic innervation of the GI tract is TRUE?

Accepted Answer

The enteric nervous system can function independently of the central nervous system. — The enteric nervous system (ENS), composed of the myenteric and submucosal plexuses, is often referred to as the 'second brain' because it can control GI function autonomously. The myenteric plexus controls motility, and the submucosal plexus controls secretion and blood flow.

Question 6

What is FALSE about tonic contractions in the GI tract?

Accepted Answer

They are absent in the stomach during fasting. — Tonic contractions are present in the stomach even during fasting, forming the migrating motor complex (MMC), which clears the stomach and small intestine between meals. They are also crucial for sphincter function and continuous mixing.

Question 7

Which of the following is characteristic of the segmenting movements in the small intestine?

Accepted Answer

Mix the chyme with digestive juices and expose it to the absorptive surfaces. — Segmentation is a non-propulsive mixing movement characterized by localized contractions of the circular muscle that churn the chyme, mixing it with digestive secretions and bringing it into contact with the mucosal lining for absorption. Peristalsis is responsible for propulsion.

Question 8

Secretion of saliva increases in all of the below except:

Accepted Answer

Chewing dry crackers — While chewing generally stimulates saliva, dry crackers are difficult to masticate and can lead to a feeling of dryness, which might initially reduce saliva flow or the sensation of it. Smell, nausea, and parasympathetic stimulation are all strong stimuli for salivation.

Question 9

Defecation is best described as:

Accepted Answer

A reflex action involving parasympathetic and somatic innervation. — Defecation is a complex reflex initiated by the distension of the rectum. It involves involuntary relaxation of the internal anal sphincter (parasympathetic control) and voluntary relaxation of the external anal sphincter (somatic control), along with increased intra-abdominal pressure.

Question 10

In the stomach, which of the following cells are responsible for secreting intrinsic factor?

Accepted Answer

Parietal cells — Parietal cells in the gastric glands are responsible for secreting both hydrochloric acid (HCl) and intrinsic factor. Intrinsic factor is crucial for the absorption of vitamin B12 in the ileum.

Question 11

Intestinal secretions contain:

Accepted Answer

Enteropeptidase — Enteropeptidase (also known as enterokinase) is an enzyme secreted by the duodenal brush border. It activates trypsinogen to trypsin, which is essential for the activation of other pancreatic proteases and is therefore considered an intestinal secretion involved in digestion.

Question 12

A 55-year-old man with chronic alcohol consumption presents with nonspecific complaints of dyspepsia. Examination reveals destruction of gastric glands. This predisposes him to:

Accepted Answer

Vitamin B12 deficiency — Destruction of gastric glands, particularly involving parietal cells, leads to decreased production of hydrochloric acid and intrinsic factor. Reduced intrinsic factor impairs vitamin B12 absorption, leading to pernicious anemia.

Question 13

Gastrin, a major GI hormone, is released in response to:

Accepted Answer

Presence of amino acids and peptides in the stomach lumen — Gastrin release from G cells in the stomach is primarily stimulated by the presence of partially digested proteins (amino acids and peptides) in the stomach. High gastric pH inhibits gastrin release.

Question 14

Vasoactive intestinal peptide (VIP) primarily causes:

Accepted Answer

Stimulation of pancreatic bicarbonate secretion — VIP is a key stimulator of pancreatic bicarbonate and fluid secretion, helping to neutralize acidic chyme entering the duodenum. It also relaxes smooth muscle in the gut and promotes vasodilation.

Question 15

Stimulation of gastrointestinal secretion is primarily mediated by:

Accepted Answer

Parasympathetic nervous system activation — The parasympathetic nervous system (via the vagus nerve and pelvic nerves) is the major stimulator of exocrine secretions from the GI tract, including saliva, gastric juices, pancreatic enzymes, and intestinal secretions.

Question 16

The hormone secretin is primarily released in response to:

Accepted Answer

Acidic chyme entering the duodenum — Secretin is released from S cells in the duodenal mucosa when acidic chyme enters the duodenum. Its main function is to stimulate the pancreas to secrete bicarbonate-rich fluid, neutralizing the acid.

Question 17

Inhibition of the myenteric plexus would most likely lead to:

Accepted Answer

Decreased propulsive movement of chyme — The myenteric plexus is crucial for coordinating and generating peristaltic waves. Inhibition would impair these propulsive movements, leading to slowed transit of chyme.

Question 18

Stimulation of the submucosal plexus results in an increase in:

Accepted Answer

Glandular secretion — The submucosal plexus (Meissner's plexus) is primarily responsible for regulating the secretory activity of the intestinal glands and influencing local blood flow.

Question 19

Regarding GIT hormones affecting gastric function, which statement is correct?

Accepted Answer

Gastrin stimulates gastric acid secretion. — Gastrin is a potent stimulator of gastric acid secretion from parietal cells. CCK and secretin generally inhibit gastric emptying and acid secretion, while GIP also inhibits gastric emptying.

Question 20

Cholecystokinin (CCK) is released in response to:

Accepted Answer

Amino acids and fatty acids in the duodenum — CCK is secreted by I cells in the duodenum and jejunum primarily in response to the presence of fatty acids and amino acids in the small intestine. It stimulates gallbladder contraction, pancreatic enzyme secretion, and inhibits gastric emptying.

Question 21

The major factor that stimulates the release of secretin into the bloodstream is:

Accepted Answer

Low pH of chyme entering the duodenum — Secretin release is triggered by the acidity of chyme entering the duodenum from the stomach. It acts to buffer this acid by stimulating bicarbonate secretion from the pancreas and liver.

Question 22

It is known that gastrin:

Accepted Answer

Stimulates the secretion of pepsinogen. — Gastrin, secreted by G cells in the stomach, stimulates the secretion of gastric acid and pepsinogen from chief cells. It also promotes gastric motility.

Question 23

It is known that secretin:

Accepted Answer

Stimulates pancreatic bicarbonate secretion. — Secretin is released in response to acid in the duodenum and primarily stimulates the pancreas to release bicarbonate-rich fluid, which buffers the acid. It also inhibits gastric acid secretion and motility.

Question 24

Concerning the gastrin hormone:

Accepted Answer

It promotes growth of the gastric and intestinal mucosa. — Gastrin has a trophic effect on the gastric and intestinal mucosa, promoting their growth and maintenance. It is secreted by G cells in the stomach, not S cells in the duodenum, and stimulates gastric acid secretion.

Question 25

Which of the following statements about the absorption of water and electrolytes in the small intestine is FALSE?

Accepted Answer

Potassium absorption is primarily an active process. — Potassium absorption in the small intestine occurs passively down its electrochemical gradient, and also via paracellular routes. While some active transport mechanisms for potassium exist, it's not the primary mode of absorption like it is for sodium.

Question 26

Which statement about fat digestion and absorption is correct?

Accepted Answer

Fat digestion begins significantly in the stomach. — Lingual lipase, secreted in the mouth and activated in the stomach, begins some fat digestion. Bile salts are crucial for forming micelles, which solubilize fatty acids and monoglycerides for absorption, but they don't hydrolyze triglycerides. Triglycerides are hydrolyzed by pancreatic lipase.

Question 27

Which statement about protein digestion is most correct?

Accepted Answer

Absorption of amino acids occurs against their concentration gradient. — Protein digestion begins in the stomach with pepsin. Pepsinogen is activated by HCl and then by pepsin itself. While some amino acids are absorbed directly, many are absorbed as di- and tripeptides, which are then further broken down intracellularly. Amino acid absorption involves both passive and active transport.

Question 28

Which statement about dietary fiber is most correct?

Accepted Answer

Soluble fiber increases stool bulk. — Dietary fiber is indigestible by human enzymes. Soluble fiber dissolves in water, forming a gel that can help regulate blood sugar and cholesterol. Insoluble fiber adds bulk to stool and aids in transit. Colonic bacteria ferment both types of fiber, producing short-chain fatty acids.

Question 29

Which statement about absorption in the small intestine is most correct?

Accepted Answer

Iron absorption is regulated by the body's iron stores. — Iron absorption is tightly regulated. Vitamin B12 is absorbed in the ileum with intrinsic factor. Fructose is absorbed via facilitated diffusion, not secondary active transport. Carbohydrate absorption involves both active transport (glucose, galactose) and facilitated diffusion (fructose).

Question 30

Which statement about the oral phase of digestion is INCORRECT?

Accepted Answer

The pharyngeal phase is initiated voluntarily. — The oral phase is voluntary. However, the pharyngeal phase of swallowing, which follows the oral phase, is involuntary. The pharyngeal phase is initiated by the voluntary movement of the bolus to the back of the mouth.

Question 31

Which statement about stomach lining cells is correct?

Accepted Answer

G cells secrete gastrin. — G cells in the gastric antrum secrete gastrin. Parietal cells secrete HCl and intrinsic factor. Chief cells secrete pepsinogen. Mucous neck cells secrete mucus.

Question 32

Which statement about pancreatic enzyme secretion is correct?

Accepted Answer

Pancreatic lipase requires bile salts for its activity. — Pancreatic lipase is the primary enzyme for triglyceride digestion and requires bile salts for optimal function by forming micelles. Pancreatic amylase digests carbohydrates. Trypsinogen is activated by enterokinase. Bicarbonate secretion is stimulated by secretin, not gastrin.

Question 33

Which statement about post-meal motility is correct?

Accepted Answer

Peristaltic waves become more frequent and vigorous. — After a meal, the gastrointestinal tract exhibits increased motility, characterized by more frequent and vigorous peristaltic contractions to propel food through the digestive system. The MMC is more prominent during the fasting state.

Question 34

Which best describes colonic microbiota functions?

Accepted Answer

Synthesis of vitamin K and B vitamins. — Colonic bacteria synthesize essential vitamins like vitamin K and several B vitamins (e.g., biotin, folate). They also ferment indigestible carbohydrates, producing short-chain fatty acids, but do not digest major nutrients or produce digestive enzymes for the host.

Question 35

What explains fiber's protective effect against colon cancer?

Accepted Answer

Increased transit time, reducing exposure to carcinogens. — Dietary fiber, particularly insoluble fiber, increases stool bulk and speeds up intestinal transit. This reduces the time that the colonic mucosa is exposed to potential carcinogens present in the fecal matter.

Question 36

Which statement regarding the swallowing reflex is false?

Accepted Answer

The soft palate elevates to prevent nasal regurgitation during the oral phase. — The soft palate elevates during the pharyngeal phase of swallowing to prevent food from entering the nasopharynx. During the oral phase, the tongue propels the bolus backward.

Weekly Year 2: GIT Physiology Exam - May 15, 2026 (Section A

Questions, Answers & Explanations